Push bench method and apparatus



June -15, 1937. w. H. ENGELBERTZ PUSH BENCH METHOD AND APPARATUS Filed.Feb. 17, 1934 R o N E V N I Patented June 15, 1937 UNITED STATES FATEOFFICE 8 Claims.

This invention has relation to the manufacture of seamless tubes andother tubular articles from cupped work-pieces upon apparatus of thepushbench type, or by the use of a new system comprising a pushbenchcooperating with a rolling mill.

The process of manufacturing tubular articles from cupped work-piecesupon apparatus of the pushbench type was originated by Ehrhardt,

United States Patent No. 495,245 of April 11, 1893,

and consisted in first bringing a solid billet to a hollow form closedat one end, and then forcing it, whilst'upon the forward end of amandrel, through reducing means until a tube was formed along themandrel from the hollow billet or workpiece. Then the tube had to bedeformed slightly by pressure rolls or the like to loosen its hold uponthe mandrel, to permit the necessary tubeand-mandrel stripping operationto be performed.

Since its origination, this process has been further developed, forinstance, the loosening of the tube on the mandrel by a reeling machineof old and well known, design was added. The tube, adhering tightly tothe mandrel, is slight- 1y increased in diameter While passing thecross-rolls of the reeling machine, thus making its removal from themandrel easier than devised by Ehrhardt. Then, the tube, after beingseparated from the mandrel, is conveyed through 3 truing means whichshape its cross-section into elongating and forming the work-piece intoa tube; second, conveying the mandrel with the tightly adhering tubethrough the cross-rolls of a reeling machine to loosen the hold of thetube upon the mandrel while leaving the structure of the metal in thetube substantially unchanged;

third, passing the tube, after the same has been separated from themandrel, through the rolls of a sizing machine which true and shape thetube to the required circular cross-section.

Practice reveals the setbacks of this necessity .of reeling the tube toenlarge its diameter sufficiently to allow the stripping of the tubefrom the mandrel. For instance, when the tube-wall .varies in thickness,a tube of varying diameter is obtained due to the'irregular amount ofpressure exerted by the reeling rolls. Therefore, the tube, after.leaving the reeling machine, must be brought to the exact diameter bypassing the sizing machine. Such unfavorable factors naturally result inadditional labor and operating expenses.

The principal object of this invention is to simplify the production oftubes and other tubular articles on the pushbench type of apparatus, oron apparatus of the said type in combination with a rolling mill bydispensing with the use of the reeling machine and the sizing machine,thus reducing the number of steps for the manufacture of such articles.In this manner, by obtaining quality products in larger quantities thanheretofore, manufacturing costs will be reduced considerably because theomission of said machines in the tube-manufacturing process is alsoatime and power saving achievement which preserves the heat of theproduct, thereby permitting its further hot-treatment without reheating.

More specifically stated, the object of this invention is to improve theprocess of manufacturing tubular articles from cupped work-pieces overmandrels to the end that, while omitting both, the reeling and thesizing machine, the tubular product formed upon the mandrel will, afterpassing its forming dies in one continuous operation and in a straightforward direction, have: first, a slightly larger internal diameter thanthe diameter of the mandrel; second, a perfect circular cross-section,trued in diameter throughout; third, an even and smooth wall and acylindrical form along its entire length.

Having in mind this briefintroduction to the invention, these and otheradvantages comprehended by the same will be fully demonstrated as thedescription progresses, and will be particularly pointed out in theappended claims.

Reference may now be made to the accompanying drawing which illustratesseveral preferred embodiments of the invention. I desire to have itunderstood that I do not intend to in any way limit myself to anyspecific details of design and construction shown in the drawing, inwhich: Fig. 1 is a diagrammatic sectional View of the dies forstretching a cupped, thick-walled short wlork-piece into a tubular bodyby passing the work-piece, supported by the forward end of the mandrel,together with the mandrel through the dies. Fig. 2 is a diagrammaticsectional view of the work-piece-stretching dies and the tubeformingrolling means. Fig. 3 is a fragmentary layout of a further developedtype of tubeforming apparatus according to this invention.

Fig. 4 is an enlarged cross-section of the cupped work-piece with themandrel inside of it, taken on line II in Figs. 1 and 2. Figs. 5 to 13,inclusive, show enlarged cross-sections of the workpiece in thesuccessive passes of the dies and rolls.

In the apparatus shown by Fig. 1, the workpiece I, carried by theforward end of mandrel 2, will, together with the mandrel, be forcedthrough dies 3, 4, 5, 6, 6 in arrow direction A, thereby reducing thecross-section of, and elongating, the work-piece into a hollow body I.During and after the forming operation the rollers 8 may support themandrel with workpiece or hollow body, respectively. The workpiece,before passing the dies, is of circular crosssection and has a boreslightly larger than the diameter of the cylindrical mandrel, as shownin Fig. 4. The dies 3, 4, 5, 6, however, which gradually decrease insize, may be oval-shaped and, preferably, located alternately inhorizontal and vertical planes as shown, whereby the workpiece may besubjected successively and alternately to pressure first from the topand bottom and then from the two sides.

The effect of the oval-shaped dies is to give the work-piece a somewhatelliptical cross-section with a larger internal circumference than thecircumference of the mandrel, thus causing the work-piece to bulgelaterally away from the mandrel, as shown in Figs. 5 to 8, inclusive. Asthe elliptically-shaped work-piece moves forward with the mandrel, it isconverted into cylindrical form when passing the circular-shaped die 6',as clearly shown in Fig. 9. In this way a truly cylindrical hollow bodyI, having an internal diameter slightly larger thanthe diameter ofmandrel 2,-thereby dispensing with a reeling machineis formed, with asmooth surface inside and out, trued in diameter-thereby omitting thesizing machine-and with a uniform wall-thickness throughout. Theseparation of mandrel and hollow body in the well known manner mayfollow immediately, after die 6' has been passed.

In the apparatus shown by Fig. 2, which comprises another embodiment ofthe invention, the work-piece 9, carried by mandrel II), will, togetherwith the mandrel. be forced by pushing means 2| through dies II, I2, I3,which may be of the same size and caliber, and soarranged toact upon thework-piece as the dies 3, 4, 5, referred to before. The work-piece 9 maypreferably have a circular cross-section with a slightly larger borethan the diameter of the mandrel II], as shown in the drawing. Thehollow body I8, being produced over the mandrel II), by passing theoval-shaped dies II, I2, I3, will, naturally, also be transformed into asomewhat elliptical cross-section with a larger internal circumferencethan the circumference of the mandrel.

While the mandrel-and-work-piece pushing means such as, for instance,items 2|, 22, 24, in Fig. 3, may be stopped as soon as the hollow bodywith mandrel have passed the dies II, I2, I3, the power-driven roll-setsI4, I5, I6, having oval-shaped calibers preferably arranged alternatelyin horizontal and vertical planes, as shown in the drawing,automatically take over and further reduce the wall of, and elongate,the hollow body I8 which is finally formed into a trued tube I9 over themandrel by passing the circular-shaped caliber of the preferably drivenrolls II, which may be located immediately be hind roll-set I6, as shownin the drawing.

Of course, the said pushing means may, if desired, be further advancedto feed the hollow body with mandrel into the grip of roll-set I4. Therollers 26 may serve as support for the work-piece, hollow body and tubewith mandrel during and after the forming operation.

Figs. 10 to 13, inclusive, illustrate the successive actions of theroll-passes which gradually decrease in size, upon the hollow body I8,showing clearly the somewhat elliptical form of the alternatelyhorizontally and vertically arranged roll-passes I4, I5, I65, as well asthat of the hollow body, and the circular-shaped finishing roll-passI'I. Since the internal circumference of hollow body I8, while said bodypasses the oval-shaped calibers of roll-sets I4, I5, I6, is alwayslarger than the circumference of mandrel III as the result of subjectingthe hollow body successively and alternately to horizontal and verticalroll pressure, i. e. first from the top and bottom and then from thesides, or vice versa, it is natural that the final product, that is thetube I9, after passing the circular-shaped caliber of the roll-set IT,has the desired larger internal circumference than the circumference ofmandrel II) along which it has been produced from the work-piece 9 inone continuous operation. Therefore, the tube I9, coming from thefinishing roll-set H with a true diameter and a circular cross-sectionthroughout, has a slightly larger internal diameter than the diameter ofmandrel I 0.

Although no attempt has been made in the drawing toshow the precisecurvature of the dies and roll-passes, I prefer that in each of thereducing dies and reducing roll-passes a portion of at least 180 degreesof the circumference of the work-piece receives a uniform wallthickness,as indicated in Figs. 5 to 8, inclusive, and Figs. 10 to 12, inclusive.Through this provision, the use of reshaping rolls or dies is dispensedwith.

In using apparatus like that shown in Figs. 1, 2 and 3 to carry out mymethod, any suitable type and number of hollow body-forming dies andtube-forming rolls, respectively, may be employed, and each roll-set mayconsist of two or more rolls. Moreover, the fixed dies 3, 4, etc., maybe replaced by idler or driven rolls. When using the latter, the actionof the pushing means may be limited to the feeding of the workpiece withmandrel into the grip of the first rollset. I prefer, however, to haveall dies, rotating or non-rotating, so spaced to each other as to haveonly one die at a time acting upon the work-piece in order to keep thematerial stress within the work-piece during its transformation down tothe best-possible minimum, and to secure the desired clearance betweenthe mandrel and hollow body, and between the mandrel and tube, duringand after the forming procedure, as specifically described before.

Another advantage of such die and roll arrangement is the elimination ofupsetting the mandrel and tearing of the bottom of the workpiece, andthe elimination of friction between work-piece and mandrel while passingthe rollsets. As shown in Fig. 2, the tube-truing rollset I! is placedclose to roll-set I6. This is permissible because no reduction of thehollow body takes place in the tube-truing pass II. Consequently, thereis no friction between tube I9 and mandrel IIl while passing thecircular-shaped caliber of roll-set II.

In accordance with the invention, the tube forming apparatus shown byFig. 2 may be extended by the facilities indicated somewhatfragmentarily in Fig. 3, in order to obtain a great increase in theoutput rate of the apparatus,

while, on the other hand, decreasing its power consumption relatively,thus operating the whole plant with the best-possible efficiency. Fig. 3shows the mandrel-and-work-piece pushing means 2|, 22, 24, driven bypinion 23, in a position after completion of the hollow body formingoperation in direction of arrow A, that is, just when roll-sets id etc.automatically take over the hollow body with mandrel to further reduceand elongate said hollow body into a tube 19, as ex plained in detailbefore. The said pushing means, however, on their reverse stroke indirection of arrow B, may feed mandrel 25 into the workpiece 26, both ofwhich are shown in dotted lines, and further advance and force themandrel, with the work-piece at its forward end, through dies 21, 28,29, thereby forming a hollow body from said work-piece along themandrel. Although it has become known to force a cupped work-piece,carried by a mandrel, through circular-shaped dies in the push bench bythe forward motion of the pushing means and, subsequently, by theirreverse stroke, each time producing a tube which adheres tightly to themandrel, the present invention provides means for drawing of tubulararticles which adhere loosely to the mandrel during and after theforming operation. Then, while the motion of the pushing means is againreversed, the hollow body with mandrel 25 is taken over by the roll-setsts etc. which transform the hollow body into a tube in the same manneras explained before. The rollers 30 may support the work-piece, hollowbody and tube with mandrel during and after the forming operation.

The advantages of my invention will be apparent to those experienced inthe art. By using my method, a heated, short and thick-walled cuppedwork-piece will be transformed into a tubular body or into a thin-walledfinished tube, adhering loosely to the mandrel over which it was formedin a single heat and in one continuous operation by a straight forwardpass, that is, without stopping or changing its direction of movement,and without passing a reeling and a sizing machine.

Modifications in the construction and arrangement of the apparatus forcarrying out my method may be made without departing from thisinvention. For instance, the passes of the dies and rolls may have anysuitable curvature, and the angular displacement of the successivepasses may differ to effect the manufacture of the tubes and othertubular articles, set forth in this specification. If desired, theproduced tubes or tubular articles may be further treated to adapt themfor their particular purpose.

What I claim is: v

l. The method of transforming cupped work'- pieces into tubes overmandrels in machines of the push bench type in one operation, duringwhich the work-piece remains partially clear of the mandrel whileforcing said mandrel, with the work-piece upon its forward end, througha succession of oval-shaped reducing dies, thus obtaining a tubular bodyof oval cross-sectional form and of equal wall-thickness throughout;and,subsequently, forcing said oval-shaped tubular body While partiallyloose upon the mandrel, with said mandrel through finishing dies forreshaping said tubular body without reducing its cross-sectional area orwall-thickness, into a tube true in diameter while, simultaneously,completely clearing the tube from the mandrel along which it isproduced.

2. Improved push bench for forming tubes from cupped work-pieces in oneoperation, comprising a mandrel carrying a cupped work-piece, aplurality of successively arranged oval-shaped reducingandcircular-shaped finishing dies having a common pass line with themandrel and work-piece; a power-driven machine part for advancing andforcing the work-piece, while upon the mandrel, through the reducingdies alternately disposed to each other and successively decreasing insize, thereby alternately pressing the same parts of the circumferenceof the workpiece against the mandrel while, simultaneously, elongatingthe work-piece and forming a concentric cross-sectional portion of thesame in contact with each die and the mandrel of at least 186 degrees,thereby forcing the remaining parts of the workpiece clear of themandrel, thus gradually reducing the wall-thickness of the workpiece andtransforming the same into a cupped tubular body of oval cross-sectiona1form, partially loose on the mandrel and of equal wallthicknessthroughout; and means for further advancing and forcing said tubularbody, while partially loose upon the mandrel, through the finishing diesfor reshaping the same without reducing its cross-sectional area orwall-thickness, into a tube true in diameter while, simultaneously,completely clearing the tube from the mandrel.

3. Improved push bench for forming tubes from cupped work-pieces,comprising a mandrel carrying a cupped work-piece, a desired number ofsuccessively arranged oval-shaped'reducingand circular-shaped finishingdies having a common pass line with the mandrel and work-piece; apower-driven machine part for advancing and forcing the work-piece,whilst upon the mandrel, through the reducing dies alternately disposedto each other and successively decreasing in size, thereby alternatelypressing the same parts of the circumference of the work-piece againstthe mandrel while forming a concentric cross-sectional portion of thework-piece in contact with each die and the mandrel of at least degrees,thereby forcing the remaining parts of the workpiece clear of themandrel, thus gradually reducing the wall-thickness of the work-pieceand elongating the same into a cupped tube of oval cross-sectional form;means for further advancing and forcing, said tube, whilst upon themandrel, through the desired number of finishing dies for truing thetube in diameter and, simultaneously, completely clearing the tube fromthe mandrel; and means for reversing the direction of motion of thepower-driven machine part after a tube has been formed, clear of themandrel, to form a tube during its backward stroke; a mandrel located inthe path of the reversing machine part, carrying a cupped work-piece onits forward end, oval-shaped reducingand circular-shaped finishing dieslocated in the path of the reversing machine part which, during itsbackward stroke, forces the Work-piece, whilst upon the mandrel, throughsaid dies, whereby the work-piece is gradually reduced in wallthicknessand elongated into a cupped tube true in diameter and loose on themandrel along which it is formed.

l. Improved method of forming a tube in machines of the push bench typefrom a cupped work-piece, comprising stretching of the workpiece over amandrel by pushing the work-piece with the mandrel in one stroke througha succession of reducing dies of oval shape, alternately disposed andpreferably spaced to each other so as to have the work-piece passthrough one die at a time, which embrace the circumference of thework-piece so as to partially reduce its wallthickness alternately onopposite sides against the mandrel, thus causing the work-piece to bulgelaterally away from the mandrel, thereby transforming the work-pieceinto a tube of oval crosssectional form; and reshaping of the said tubeinto circular cross-section by passing the same through finishing diesafter leaving the reducing dies, thereby truing the tube in diameterand, simultaneously, loosening the hold of the tube on the mandrel, thusforming a cupped tube of larger internal diameter than the diameter ofthe mandrel along which the said tube is being produced.

5. Method of forming a tube from a cupped work-piece in machines of thepush bench type cooperating with rolling apparatus, which comprisesstretching of the work-piece over a mandrel by pushing the work-piecewith the mandrel in one stroke through a succession of reducing dies ofoval shape alternately disposed to each other, which embrace thecircumference of the work-piece in a manner to reduce its wall-thicknessalternately on opposite sides against the mandrel while forming aconcentric cross-sectional portion of the work-piece in contact witheach die and the mandrel of the least 180 degrees, thus causing thework-piece to partially bulge laterally away from the mandrel, therebyelongating the work-piece and transforming the same into ovalcross-sectional form; and conveying the work-piece, after leaving thedies, forward with the mandrel through a succession of roll-setspreferably spaced to each other so as to have the work-piece passthrough one roll-set at one time, and having said roll-sets form ovalpasses alternately disposed to each other, embracing the surface of thework-piece in a manner to reduce its wall-thickness alternately onopposite sides against the mandrel while forming a concentriccross-sectional portion of the workpiece in contact with each roll-setand the mandrel of at least 180 degrees, thus causing the work-piece topartially bulge laterally away from the mandrel, thereby transformingthe workpiece into a tube of oval cross-sectional form; and reshaping ofthe said tube into circular crosssection by passing the same throughfinishing rolls, thereby truing the tube in diameter and,simultaneously, loosening the hold of the tube on the mandrel, thusforming a cupped tube of larger internal diameter than the diameter ofthe mandrel along which the said tube is being produced.

6. Method of forming a tube from a cupped Work-piece in machines of thepush bench type cooperating with rolling apparatus, which comprisesstretching of the work-piece over a mandrel by pushing the work-piecewith the mandrel in one stroke through a succession of reducing dies ofoval shape, alternately disposed and preferably spaced to each other soas to have the workpiece pass through one die at a time, which embracethe circumference of the work-piece so as to partially reduce itswall-thickness alternately on opposite sides against the mandrel, thuscausing the work-piece to bulge laterally away from the mandrel, therebyelongating the work-piece and transforming the same into oval cross-seetional form; and conveying the work-piece, after leaving the dies,forward with the mandrel through a succession of roll-sets which formoval passes, alternately disposed and preferably spaced to each other soas to have the work-piece pass through one roll-set at a time, embracingthe surface of the work-piece so as to partially reduce itsWall-thickness alternately on opposite sides against'the mandrel, thuscausing the work-piece to bulge laterally away from the mandrel, therebytransforming the work-piece into a tube of oval cross-sectional form;and reshaping of the said tube into circular cross-section by passingthe same through finishing rolls, thereby truing the tube in diameterand, simultaneously, loosening the hold of the tube on the mandrel, thusforming a cupped tube of larger internal diameter than the diameter ofthe mandrel along which the said tube is being produced.

7. Apparatus for forming tubes from cupped work-pieces, comprising incombination, a push bench having a mandrel supporting a cuppedwork-piece, a plurality of successively arranged oval-shaped reducingdies having a common pass line with the mandrel and work-piece; apowerdriven machine part for advancing and forcing the work-piece,whilst upon the mandrel, through the reducing dies alternately disposedto each other and successively decreasing in size, thereby pressing onlyalternate portions of the surface of the work-piece at one time againstthe mandrel so as to have an angular contacting surface of thework-piece with each die and the mandrel of at least 180 degrees,thereby forcing the nopressure portions of the work-piece clear of themandrel, thus gradually reducing the wall-thickness of the work-pieceand elongating the same; a plurality of roll-sets in alignment with saiddies and preferably spaced to each other so as to have the work-piecepass through one roll-set at one time, having oval-shaped passesangularly disposed to each other alternately for further reducing thewall of the work-piece and elongating the same into a cupped tubepartially clear of the mandrel; and rolls in line with said rollsets,for truing the said tube in diameter and, simultaneously, completelyclearing the tube from the mandrel.

8. In apparatus according to claim 7, means for reversing the directionof motion of the powerdriven machine part after a tube has been formed,clear of the mandrel, to perform a tubeforming operation during itsbackward stroke; a mandrel located in the path of the reversed machinepart, carrying a cupped work-piece on its forward end, a plurality ofdies and roll-sets having oval-shaped passes angularly disposed to eachother alternately, and located in the path of the reversed machine partwhich, during its backward stroke, forces the work-piece through saiddies, thereby gradually reducing the diameter of the work-piece andelongating it along the mandrel; and further reducing and elongating thework-piece, whilst upon the mandrel, by passl WILLIAM H. ENGELBERTZ.

